Promoted potassium salts based Ru/AC catalysts for water gas shift reaction

In this work, we have prepared several kinds of potassium salts doped Ru/AC catalysts and systematically studied their catalytic activities towards water–gas shift (WGS) reaction. Activity testing indicated that K 2 CO 3 doped Ru/AC catalyst (Ru-K 2 CO 3 /AC) showed higher catalytic performance than KOH and KOAc doped Ru/AC catalysts, methane selectivity decreased most after doping KOH. Although the particle size of Ru nanoparticles in Ru-K 2 CO 3 /AC catalyst was larger than that of the parent Ru/AC catalyst, H 2 -TPR indicated that RuO x was reduced at much lower temperature, suggesting a weaker interaction between RuO x and the surface functional group of active carbon after the doping of K 2 CO 3 . Thus, Ru nanoparticles interacted stronger with the reaction molecules (CO and H 2 O), leading a higher catalytic activity. In addition, the doping of K 2 CO 3 on the surface of Ru/AC catalyst also increased the concentration of water around Ru active site due to the hygroscopic ability. Interestingly, it was also found that the prepared method also greatly affected the catalyst activity. If the active carbon was firstly coated with K 2 CO 3 , followed deposition of Ru metal nanoparticles, (called Ru/K 2 CO 3 -AC catalyst), the activity decreased remarkably as compared to Ru-K 2 CO 3 /AC. The low catalytic activity of Ru/K 2 CO 3 -AC was mainly due to the aggregation of Ru nanoparticles.